Suppression of testicular steroidogenesis by the GnRH agonistic analogue Buserelin (HOE-766) in patients with prostatic cancer: studies in relation to dose and route of administration.

Forty-six patients with prostatic carcinoma received the gonadotropin releasing hormone agonistic analogue (GnRH-A) Buserelin at doses ranging from 0.05 to 1.5 mg subcutaneously and/or 0.4 to 1.2 mg intranasally (i.n.) daily for 12-120 weeks. An increase in plasma testosterone (T) was seen in 19% of patients on day 7 of therapy; with continuation of treatment plasma T as well as DHT and E2 levels fell by more than 50% within 2-4 weeks in those patients receiving greater than or equal to 50 micrograms s.c. and/or greater than or equal to 1 mg in daily dose. Persistently low plasma T levels (less than 1 ng/ml) were reached in 60% of patients receiving 50 micrograms s.c. in 89% of those treated with 1.2 mg i.n. and in 100% of patients who received initially 1.5 mg s.c. X 7 days followed by 1.2 mg i.n. daily. The above data indicate the importance of dose and route of administration in achieving significant suppression of plasma sex steroids in patients with prostate cancer in whom Buserelin can be used as an alternative to castration or estrogens.